The present invention relates to a cultivating machine, and more particularly to an arrangement for coupling a cultivating machine.
With tractor-drawn combined-attachment cultivating machines, a main frame adapted to be fitted with cultivating implements, such as harrows or the like, is supported at its trailing ends on one or more roller units which trail the main frame. Each of the one or more roller units is articulately coupled to the trailing end of the main frame by means of a respective support and pressure-transmitting arm, and the coupling arrangement for each roller unit is typically provided with a screw-spindle-type adjuster for adjusting the relative elevations of the frame of the roller unit and of the main frame carrying the cultivating implements. This relative-height adjustment serves to determine the depth of penetration of the cultivating implements into the soil being tilled, because the trailing end of the main frame rests on the trailing roller unit (s).
When the threaded spindle rigidly couples the roller frames to the main frame of the machine the working depth after once being set remains invariable even in conditions of differing ground resistance. In such a construction one has to accept the fact that the individual roller units may not be able to individually rise and descend to match transverse unevenness of the ground being worked and the earth left behind the roller units will be nonuniformly worked. Furthermore, when the arrangement having the above-mentioned rigid coupling passes over obstacles, such as stones and the like, significant stresses are applied to the cultivating implements and the frames because the entire weight of the attachments displaces upwardly under the action of the obstacle.
In order to eliminate these disadvantages, it has been proposed to provide such height-adjustment spindle with shock-absorbing spring-suspension means. Such a construction possesses the disadvantage that the depth of the tool cultivating implements on the main frame no longer remains constant. Thus, the operator is forced to give preference to either rigid or else spring-suspension coupling in dependence upon the implements required and the work to be done. This results from the fact the the known cultivating machines are provided either with a rigid adjusting spindle or else with a shock-absorbing spring-suspension adjusting spindle.